1. Field of the Invention
The present invention relates to an audio signal processing circuit with reduced power consumption.
2. Description of the Related Art
In a voice recorder or the like, a process is executed where an audio signal is compressed and recorded in a non-volatile memory. In this process, an encoder IC of the voice recorder digitizes an analog signal into a digital signal with an analog/digital converter circuit, generates compressed music data with an encoder, and stores the data in the non-volatile memory.
FIG. 6 shows an example of an audio signal processing circuit 100 of related art. As shown in FIG. 6, the audio signal processing circuit 100 of related art comprises an analog/digital converter (ADC) 10, a clock controller 12, and an encoding unit 14. A non-volatile memory 102 is connected to the audio signal processing circuit 100, and an audio signal processed by the audio signal processing circuit 100 is recorded.
The ADC 10 samples an input analog audio signal at a predetermined sampling frequency, to digitize the input signal. The clock controller 12 generates a clock so that the sampling frequency of the ADC 10 is set to, for example, 44.1 kHz, and supplies the clock to the ADC 10. The encoding unit 14 encodes the audio signal which is digitized by the ADC 10 according to a predetermined compression method, and stores the encoded signal in the non-volatile memory 102.
In the audio signal processing circuit 100, as the sampling frequency of the ADC 10 is increased, the power consumption in the ADC 10 is also increased.